Image-based 3D modeling study of the influence of vessel density and blood hemoglobin concentration on tumor oxygenation and response to irradiation

PURPOSE: Hypoxia is one of the most important factors influencing clinical outcome after radiotherapy. Improved knowledge of factors affecting the levels and distribution of oxygen within a tumor is needed. The authors constructed a theoretical 3D model based on histological images to analyze the influence of vessel density and hemoglobin (Hb) concentration on the response to irradiation.METHODS: The pancreases of a Rip-Tag2 mouse, a model of malignant insulinoma, were excised, cryosectioned, immunostained, and photographed. Vessels were identified by image thresholding and a 3D vessel matrix assembled. The matrix was reduced to functional vessel segments and enlarged by replication. The steady-state oxygen tension field of the tumor was calculated by iteratively employing Green's function method for diffusion and the Michaelis-Menten model for consumption. The impact of vessel density on the radiation response was studied by removing a number of randomly selected vessels. The impact of Hb concentration was studied by independently changing vessel oxygen partial pressure (pO(2)). For each oxygen distribution, the oxygen enhancement ratio (OER) was calculated and the mean absorbed dose at which the tumor control probability (TCP) was 0.99 (D(99)) was determined using the linear-quadratic cell survival model (LQ model).RESULTS: Decreased pO(2) shifted the oxygen distribution to lower values, whereas decreased vessel density caused the distribution to widen and shift to lower values. Combined scenarios caused lower-shifted distributions, emphasising log-normal characteristics. Vessel reduction combined with increased blood pO(2) caused the distribution to widen due to a lack of vessels. The most pronounced radiation effect of increased pO(2) occurred with tumor tissue with 50% of the maximum vessel density used in the simulations. A 51% decrease in D(99), from 123 to 60 Gy, was found between the lowest and highest pO(2) concentrations.CONCLUSIONS: Our results indicate that an intermediate vascular density region exists where enhanced blood oxygen concentration may be beneficial for radiation response. The results also suggest that it is possible to distinguish between diffusion-limited and anemic hypoxia from the characteristics of the pO(2) distribution

The Swedish national guidelines on prostate cancer, part 2 : recurrent, metastatic and castration resistant disease

Objective: There is now an unprecedented amount of evidence to consider when revising prostate cancer guidelines. We believe that there is a value in publishing summaries of national clinical guidelines in English for others to read and comment on. Methods: This is part 2 of a summary of the Swedish prostate cancer guidelines that were published in June 2022. This part covers recurrence after local treatment and management of metastatic and castration resistant disease. Part 1 covers early detection, diagnostics, staging, patient support and management of non-metastatic disease. Results: The 2022 Swedish guidelines include several new recommendations. Among these is a recommendation of a period of observation with repeated PSA tests for patients with approximately 10 years’ life expectancy who experience a BCR more than 2–5 years after radical prostatectomy, to allow for estimating the PSA doubling time before deciding whether to give salvage radiotherapy or not. Recent results from the PEACE-1 trial led to the recommendation of triple-treatment with a GnRH agonist, abiraterone plus prednisolone and 6 cycles of docetaxel for patients with high-volume metastatic disease who are fit for chemotherapy. The Swedish guidelines differ from the European ones by having more restrictive recommendations about genetic testing of and high-dose zoledronic acid or denosumab treatment for men with metastatic prostate cancer, and by recommending considering bicalutamide monotherapy for selected patients with low-volume metastatic disease. Conclusions: The 2022 Swedish prostate cancer guidelines include several new recommendations and some that differ from the European guidelines

The Swedish national guidelines on prostate cancer, part 1: early detection, diagnostics, staging, patient support and primary management of non-metastatic disease

Objective: There is now an unprecedented amount of evidence to consider when revising prostate cancer guidelines. We believe that there is a value in publishing summaries of national clinical guidelines in English for others to read and comment on. Methods: This is part 1 of a summary of the Swedish prostate cancer guidelines that were published in June 2022. It covers the early detection, diagnostics, staging, patient support and management of the non-metastatic disease. Part 2 covers recurrence after local treatment and management of the metastatic disease. Results: The 2022 Swedish guidelines include several new recommendations: rectal iodine-povidone to reduce post-biopsy infections, external beam radiation with focal boost to the tumour, use of a pre-rectal spacer to reduce rectal side effects after external beam radiotherapy in some expert centres, 6 months’ concomitant and adjuvant rather than neoadjuvant and concomitant hormonal treatment together with radiotherapy for unfavourable intermediate and high-risk disease, and adjuvant abiraterone plus prednisolone together with a GnRH agonist for a subgroup of men with very high-risk disease. The Swedish guidelines differ from the European by having more restrictive recommendations regarding genetic testing and pelvic lymph node dissection, the risk group classification, recommending ultra-hypofractionated (7 fractions) external radiotherapy for intermediate and selected high-risk cancers, by not recommending any hormonal treatment together with radiotherapy for favourable intermediate-risk disease, and by recommending bicalutamide monotherapy instead of a GnRH agonist for some patient groups. Conclusions: The 2022 Swedish prostate cancer guidelines include several new recommendations and some that differ from the European guidelines

Assessing Radiographic Response to 223Ra with an Automated Bone Scan Index in Metastatic Castration-Resistant Prostate Cancer Patients

For effective clinical management of patients being treated with 223Ra, there is a need for radiographic response biomarkers to minimize disease progression and to stratify patients for subsequent treatment options. The objective of this study was to evaluate an automated bone scan index (aBSI) as a quantitative assessment of bone scans for radiographic response in patients with metastatic castration-resistant prostate cancer (mCRPC). Methods: In a multicenter retrospective study, bone scans from patients with mCRPC treated with monthly injections of 223Ra were collected from 7 hospitals in Sweden. Patients with available bone scans before treatment with 223Ra and at treatment discontinuation were eligible for the study. The aBSI was generated at baseline and at treatment discontinuation. The Spearman rank correlation was used to correlate aBSI with the baseline covariates: alkaline phosphatase (ALP) and prostate-specific antigen (PSA). The Cox proportional-hazards model and Kaplan-Meier curve were used to evaluate the association of covariates at baseline and their change at treatment discontinuation with overall survival (OS). The concordance index (C-index) was used to evaluate the discriminating strength of covariates in predicting OS. Results: Bone scan images at baseline were available from 156 patients, and 67 patients had both a baseline and a treatment discontinuation bone scan (median, 5 doses; interquartile range, 3-6 doses). Baseline aBSI (median, 4.5; interquartile range, 2.4-6.5) was moderately correlated with ALP (r = 0.60, P < 0.0001) and with PSA (r = 0.38, P = 0.003). Among baseline covariates, aBSI (P = 0.01) and ALP (P = 0.001) were significantly associated with OS, whereas PSA values were not (P = 0.059). After treatment discontinuation, 36% (24/67), 80% (54/67), and 13% (9/67) of patients demonstrated a decline in aBSI, ALP, and PSA, respectively. As a continuous variable, the relative change in aBSI after treatment, compared with baseline, was significantly associated with OS (P < 0.0001), with a C-index of 0.67. Median OS in patients with both aBSI and ALP decline (median, 134 wk) was significantly longer than in patients with ALP decline only (median, 77 wk; P = 0.029). Conclusion: Both aBSI at baseline and its change at treatment discontinuation were significant parameters associated with OS. The study warrants prospective validation of aBSI as a quantitative imaging response biomarker to predict OS in patients with mCRPC treated with 223Ra

Dosimetric analysis of the short-ranged particle emitter161 tb for radionuclide therapy of metastatic prostate cancer

The aim of this study was to analyze the required absorbed doses to detectable metastases (Dreq ) when using radionuclides with prostate specific membrane antigen (PSMA)-targeting radioligands to achieve a high probability for metastatic control. The Monte Carlo based analysis was performed for the clinically-used radionuclides yttrium-90, iodine-131, lutetium-177, and actinium-225, and the newly-proposed low-energy electron emitter terbium-161. It was demonstrated that metastatic formation rate highly influenced the metastatic distribution. Lower values generated few large detectable metastases, as in the case with oligo metastases, while high values generated a distribution of multiple small detectable metastases, as observed in patients with diffused visualized metastases. With equal number of detectable metastases, the total metastatic volume burden was 4–6 times higher in the oligo metastatic scenario compared to the diffusely visualized scenario. The Dreq was around 30% higher for the situations with 20 detectable metastases compared to one detectable metastasis. The Dreq for iodine-131 and yttrium-90 was high (920–3300 Gy). The Dreq for lutetium-177 was between 560 and 780 Gy and considerably lower Dreq were obtained for actinium-225 and terbium-161, with 240–330 Gy and 210–280 Gy, respectively. In conclusion, the simulations demonstrated that terbium-161 has the potential for being a more effective targeted radionuclide therapy for metastases using PSMA ligands

Patient-reported side effects 1 year after radical prostatectomy or radiotherapy for prostate cancer : a register-based nationwide study

BACKGROUND: Data on functional and psychological side effects following curative treatment for prostate cancer are lacking from large, contemporary, unselected, population-based cohorts. OBJECTIVE: To assess urinary symptoms, bowel disturbances, erectile dysfunction (ED), and quality of life (QoL) 12 mo after robot-assisted radical prostatectomy (RARP) and radiotherapy (RT) using patient-reported outcome measures in the Swedish prostate cancer database. DESIGN, SETTING, AND PARTICIPANTS: This was a nationwide, population-based, cohort study in Sweden of men who underwent primary RARP or RT between January 1, 2018 and December 31, 2020. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Absolute proportions and odds ratios (ORs) were calculated using multivariable logistic regression, with adjustment for clinical characteristics. RESULTS AND LIMITATIONS: A total of 2557 men underwent RARP and 1741 received RT. Men who underwent RT were older (69 vs 65 yr) and had more comorbidities at baseline. After RARP, 13% of men experienced incontinence, compared to 6% after RT. The frequency of urinary bother was similar, at 18% after RARP and 18% after RT. Urgency to defecate was reported by 14% of men after RARP and 34% after RT. At 1 yr, 73% of men had ED after RARP, and 77% after RT. High QoL was reported by 85% of men after RARP and 78% of men after RT. On multivariable regression analysis, RT was associated with lower risks of urinary incontinence (OR 0.25, 95% confidence interval [CI] 0.19-0.33), urinary bother (OR 0.79, 95% CI 0.66-0.95), and ED (OR 0.54, 95% CI 0.46-0.65), but higher risk of bowel symptoms (OR 2.86, 95% CI 2.42-3.39). QoL was higher after RARP than after RT (OR 1.34, 95% CI 1.12-1.61). CONCLUSIONS: Short-term specific side effects after curative treatment for prostate cancer significantly differed between RARP and RT in this large and unselected cohort. Nevertheless, the risk of urinary bother was lower after RT, while higher QoL was common after RARP. PATIENT SUMMARY: In our study of patients treated for prostate cancer, urinary bother and overall quality of life are comparable at 1 year after surgical removal of the prostate in comparison to radiotherapy, despite substantial differences in other side effects

Comparative Effectiveness of Different Radical Radiotherapy Treatment Regimens for Prostate Cancer : A Population-Based Cohort Study

Background: It is unclear which radiotherapy technique and dose fractionation scheme is most effective in decreasing the risk of prostate cancer death. Methods: We conducted a population-based cohort study among 15 164 men in the Prostate Cancer database Sweden (version 4.0) treated with primary radical radiotherapy for prostate cancer in Sweden from 1998 to 2016. We calculated hazard ratios with 95% confidence intervals (CIs) of the association between the following exposure groups and outcome: conventionally fractionated external beam radiotherapy (EBRT) to 78 Gy (39 × 2 Gy), EBRT combined with high dose-rate brachytherapy (HDR-BT) (25 × 2 Gy + 2 × 10 Gy), conventionally fractionated EBRT to 70 Gy (35 × 2 Gy), and moderately hypofractionated (M-HF) dose-escalated EBRT (29 × 2.5 Gy or 22 × 3 Gy). Results: Of the men, 7296 received conventionally fractionated EBRT to 78 Gy, 4657 EBRT combined with HDR-BT, 1672 conventionally fractionated EBRT to 70 Gy, and 1539 M-HF EBRT. Using EBRT to 78 Gy as the reference, the multivariable hazard ratios (95% CIs) of prostate cancer death was 0.64 (0.53 to 0.78) for EBRT combined with HDR-BT, 1.00 (0.80 to 1.27) for EBRT to 70 Gy, and 1.51 (0.99 to 2.32) for M-HF EBRT. The multivariable hazard ratios (95% CIs) for death from any cause were 0.79 (0.71 to 0.88), 0.99 (0.87 to 1.14), and 1.12 (0.88 to 1.42), respectively. The lower risk of prostate cancer death comparing EBRT combined with HDR-BT with conventionally fractionated EBRT to 78 Gy was more pronounced for men with high-risk or poorly differentiated tumors. Conclusions: In this study, EBRT combined with HDR-BT was the most effective radiotherapy treatment regimen, especially for poorly differentiated tumors. Randomized trials comparing EBRT combined with HDR-BT with dose-escalated EBRT should be a priority

Liver-derived IGF1 enhances the androgenic response in prostate.

Both IGF1 and androgens are major enhancers of prostate growth and are implicated in the development of prostate hyperplasia and cancer. The aim of the present study was to investigate whether liver-derived endocrine IGF1 modulates the androgenic response in prostate. Mice with adult, liver-specific inactivation of IGF1 (LI-IGF1(-/-) mice) displayed an approximately 80% reduction in serum IGF1 levels associated with decreased prostate weight compared with control mice (anterior prostate lobe -19%,